This was the first case of back-to-back mass bleaching events on the reef. The result was a 30% loss of corals in 2016, a further 20% loss in 2017, and big changes in community structure. New research published in Nature today now reveals the damage that these losses caused to the wider ecosystem functioning of the Great Barrier Reef.

Fast-growing staghorn and tabular corals suffered a rapid, catastrophic die-off, changing the three-dimensional character of many individual reefs. In areas subject to the most sustained high temperatures, some corals died without even bleaching – the first time that such rapid coral death has been documented on such a wide scale.

The research team, led by Terry Hughes of James Cook University, carried out extensive surveys during the two bleaching events, at a range of scales.

First, aerial surveys from planes generated thousands of videos of the reef. The data from these videos were then verified by teams of divers in the water using traditional survey methods.

Finally, teams of divers took samples of corals and investigated their physiology in the laboratory. This included counting the density of the microalgae that live within the coral cells and provide most of the energy for the corals.

The latest paper follows on from earlier research which documented the 81% of reefs that bleached in the northern sector of the Great Barrier Reef, 33% in the central section, and 1% in the southern sector, and compared this event with previous bleaching events. Another previous paper documented the reduction in time between bleaching events since the 1980s, down to the current interval of one every six years.

Although reef scientists have been predicting the increased frequency and severity of bleaching events for two decades, this paper has some surprising and alarming results. Bleaching events occur when the temperature rises above the average summer maximum for a sufficient period. We measure this accumulated heat stress in “degree heating weeks” (DHW) – the number of degrees above the average summer maximum, multiplied by the number of weeks. Generally, the higher the DHW, the higher the expected coral death.

In the 2016 event, however, bleaching began at 2 DHW and corals began dying at 3 DHW. Then, as the sustained high temperatures continued, coral death accelerated rapidly, reaching more than 50% mortality at only 4-5 DHW.

Many corals also died very rapidly, without appearing to bleach beforehand. This suggests that these corals essentially shut down due to the heat. This is the first record of such rapid death occurring at this scale.

This study shows clearly that the structure of coral communities in the northern sector of the reef has changed dramatically, with a predominant loss of branching corals. The post-bleaching reef has a higher proportion of massive growth forms which, with no gaps between branches, provide fewer places for fish and invertebrates to hide. This loss of hiding places is one of the reasons for the reduction of fish populations following severe bleaching events.

The International Union for Conservation of Nature (IUCN), which produces the Red List of threatened species, recently extended this concept to ecosystems that are threatened with collapse. This is difficult to implement, but this new research provides the initial and post-event data, leaves us with no doubt about the driver of the change, and suggests threshold levels of DHWs. These cover the requirements for such a listing.

Predictions of recovery times following these bleaching events are difficult as many corals that survived are weakened, so mortality continues. Replacement of lost corals through recruitment relies on healthy coral larvae arriving and finding suitable settlement substrate. Corals that have experienced these warm events are often slow to recover enough to reproduce normally so larvae may need to travel from distant healthy reefs.

Although this paper brings us devastating news of coral death at relatively low levels of heat stress, it is important to recognise that we still have plenty of good coral cover remaining on the Great Barrier Reef, particularly in the southern and central sectors. We can save this reef, but the time to act is now.

This is not just for the sake of our precious Great Barrier Reef, but for the people who live close to reefs around the world that are at risk from climate change. Millions rely on reefs for protection of their nations from oceanic swells, for food and for other ecosystem services.

This research leaves no doubt that we must reduce global emissions dramatically and swiftly if we are save these vital ecosystems. We also need to invest in looking after reefs at a local level to increase their chances of surviving the challenges of climate change. This means adequately funding improvements to water quality and protecting as many areas as possible.

In the northern part of Australia’s Great Barrier Reef, the future for green sea turtles appears to be turning female.

A recent study has revealed that climate change is rapidly leading to the feminisation of green turtles in one of the world’s largest populations. Only about 1% of these juvenile turtles are hatching male.

Among sea turtles, incubation temperatures above 29ºC produce more female offspring. When incubation temperatures approach 33ºC, 100% of the offspring are female. Cooler temperatures yield more males, up to 100% near a lower thermal limit of 23ºC. And if eggs incubate at temperatures outside the range of 23-33ºC the risk of embryo malformation and mortality becomes very high.

As current climate change models foresee increases in average global temperature of 2 to 3ºC by 2100, the future for these turtles is in danger. Worryingly, warmer temperatures will also lead to ocean expansion and sea-level rise, increasing the risk of flooding of nesting habitats.

How scientists are tackling the problem

Green sea turtles’ sensitivity to incubation temperatures is such that even a few degrees can dramatically change the sex ratio of hatchlings.

Sea turtles are particularly vulnerable because they have temperature-dependent sex determination, or TSD, meaning that the sex of the offspring depends on the incubation temperature of the eggs. This is the same mechanism that determines the sex of several other reptile species, such as the crocodilians, many lizards and freshwater turtles.

Scientists and conservationists are well aware of how future temperatures may threaten these species. For the past two decades they have been investigating the incubation conditions and resulting sex ratios at several sea turtle nesting beaches worldwide.

This is mostly done using temperature recording devices (roughly the size of an egg). These are placed inside nest chambers among the clutch of eggs, or buried in the sand at the same depth as the eggs. When a clutch hatches (after 50 to 60 days) the device is recovered and the temperatures recorded are analysed.

Research has revealed that most nesting beaches studied to date have sand temperatures that favour female hatchling production. But this female bias is not immediately a bad thing, because male sea turtles can mate with several females (polygyny). So having more females actually enhances the reproductive potential of a population (i.e. more females equals more eggs).

But given that climate change will likely soon increase this female bias, important questions arise. How much of a female bias is OK? Will there be enough males? What is the minimum proportion of males to keep a sustainable population?

These questions are being investigated. But, in the meantime, alarming reports of populations with more than 99% of hatchlings being female stress the urgency of science-based management strategies. These strategies must be designed to promote (or maintain) cooler incubation temperatures at key nesting beaches to prevent population decline or even extinction.

Coastal vegetation also protects the nesting beach against wave erosion during storms, which will worsen under climate change. This strategy further requires coastal development to allow for buffer zones. Construction setback regulations should be enforced or implemented.

When natural shading is not an option, clutches of eggs can be moved either to more suitable beaches, or to hatcheries with artificial shading. Researchers have tested the use of synthetic shade cloth and found it is effective in reducing sand and nest temperatures.

Other potential strategies involve adding light-coloured sand on top of nests. This can help by absorbing less solar radiation (heat) compared to darker sand. Beach sprinklers have also been tested to simulate the cooling effect of rainfall.

The effectiveness of these actions has yet to be fully tested, but there is concern about some potential negative side effects. For example, excess water from sprinklers may cause fungal infections on eggs.

Finally, as much as mitigation measures are important, these are always short-term solutions. In the long run, prevention is always the best strategy, i.e. protecting the nesting beaches that currently produce more males from deforestation, development and habitat degradation.

Our recent research on the largest green turtle population in Africa reports unusually high male hatchling production. We found almost balanced hatchling sex ratios (1 female to 1.2 males). We attributed this mostly to the cooling effect of the native forest.

This, and similar nesting beaches, should be designated as priority conservation sites, as they will be key to ensuring the future of sea turtles under projected global warming scenarios.

Sea turtles face an uncertain future

Sea turtles are resilient creatures. They have been around for over 200 million years, surviving the mass extinction that included the dinosaurs, and enduring dramatic climatic changes in the past.

There is potential for these creatures to adapt, as they did before. This could be through, for example, shifting the timing of nesting to cooler periods, changing their distribution to more suitable habitats, or evolution of critical incubation temperatures that produce males.

But the climate today is changing at an unprecedented rate. Along with the feminisation of these turtles in the northern Great Barrier Reef, sea turtles globally face many threats from humans. These include problems associated with by-catch, poaching, habitat degradation and coastal development, plus a history of intense human exploitation.

In 2018, the prevalence of these species depends now more than ever on the effectiveness of conservation measures.

We have discovered a new species of orangutan – the third known species and the first new great ape to be described since the bonobo almost a century ago.

The new species, called the Tapanuli orangutan (Pongo tapanuliensis), has a smaller skull than the existing Bornean and Sumatran orangutans, but has larger canines.

As we and our colleagues report in the journal Current Biology, the new species is represented by an isolated population of fewer than 800 orangutans living at Batang Toru in northern Sumatra, Indonesia.

Orangutan populations in Sumatra and Borneo – the new species’ distribution is shown in yellow.Curr. Biol.

The existence of a group of orangutans in this region was first reported back in 1939. But the Batang Toru orangutans were not rediscovered until 1997, and then confirmed in 2003. We set about carrying out further research to see whether this isolated group of orangutans was truly a unique species.

On the basis of genetic evidence, we have concluded that they are indeed distinct from both the other two known species of orangutan: Pongo abelii from further north in Sumatra, and Pongo pygmaeus from Borneo.

The Batang Toru orangutans have a curious mix of features. Mature males have cheek flanges similar to those of Bornean orangutans, but their slender build is more akin to Sumatran orangutans.

The hair colour is more cinnamon than the Bornean species, and the Batang Toru population also makes longer calls than other orangutans.

Making sure

To make completely sure, we needed more accurate comparisons of their body dimensions, or “morphology”. It was not until 2013 that the skeleton of an adult male became available, but since then one of us (Anton) has amassed some 500 skulls of the other two species, collected from 21 institutions, to allow for accurate comparisons.

Analyses have to be conducted at a similar developmental stage on male orangutan skulls, because they continue growing even when adult. Anton found 33 skulls of wild males that were suitable for comparison. Of 39 different measurement characteristics for the Batang Toru skull, 24 of them fall outside of the typical ranges of northern Sumatran and Bornean orangutans.

The new orangutans have smaller heads – but some impressive teeth.Matthew G Nowak, Author provided

Overall the Batang Toru male has a smaller skull, but bigger canines. Combining the genetic, vocal, and morphological sources of evidence, we have confidently concluded that Batang Toru orangutan population is a newly discovered species – and one whose future is already under threat.

Under threat as soon as they’re discovered.Maxime Aliaga, Author provided

Despite the heavy exploitation of the surrounding areas (hunting, habitat
alteration and other illegal activities), the communities surrounding the habitat of the Tapanuli orangutan still give us the opportunity to see and census the surviving population. Unfortunately, we believe that the population is fewer than 800 individuals.

Of the habitat itself, no more than 10 square km remains. Future development has been planned for that area, and about 15% of the orangutans’ habitat has non-protected forest status.

The discovery of the third orangutan in the 21st century gives us an understanding that the great apes have more diversity than we know, making it all the more important to conserve these various groups.

Without the strong support of, and participation from, the communities surrounding its habitat, the future of the Tapanuli orangutan will be uncertain. Government, researchers and conservation institutions must make a strong collaborative effort to make sure that this third orangutan will survive long after its discovery.

Mercury pollution has a long legacy in the environment. Once released into the air, it can cycle between the atmosphere and ecosystems for years or even decades before ending up deep in the oceans or land.

To address the global and long-lasting mercury problem, a new United Nations treaty called the Minamata Convention on Mercury came into effect last month. The treaty commits participating countries to limit the release of mercury and monitor the impacts on the environment. Australia signed the Convention in 2013 and is now considering ratification.

Until now, we have only been able to guess how much mercury might be in the air over tropical Australia. Our new research, published in the journal Atmospheric Chemistry and Physics, shows that there is less mercury in the Australian tropics than in the northern hemisphere – but that polluted northern hemisphere air occasionally comes to us.

Small-scale gold mining is an economic mainstay for millions of people, but it releases mercury directly into the air and water sources.

Once released to the air, mercury can travel thousands of kilometres to end up in ecosystems far away from the original source.

Measuring mercury in the tropics

While the United Nations was gathering signatures for the Minamata Convention, we were busy measuring mercury at the Australian Tropical Atmospheric Research Station near Darwin. Our two years of measurements are the first in tropical Australia. They are also the only tropical mercury measurements anywhere in the Maritime Continent region covering southeast Asia, Indonesia, and northern Australia.

More surprising is the seasonal pattern in the data. There is more mercury in the air during the dry season than the wet season.

The Australian monsoon appears to be partly responsible for the seasonal change. The amount of mercury jumps up sharply at the start of the dry season when the winds shift from blowing over the ocean to blowing over the land.

In the dry season the air passes over the Australian continent before arriving at the site, while in the wet season the air usually comes from over the ocean to the west of Darwin.Howard et al., 2017 (modified)

But wind direction can’t explain the whole story. Mercury is likely being removed from the air by the intense rains that characterise the wet season. In other words, the lower mercury in the air during the wet season may mean more mercury is being deposited to the ocean and the land at this time of year. Unfortunately, there simply isn’t enough information from Australian ecosystems to know how this impacts local plants and wildlife.

Fires also play a role. Mercury previously absorbed by grasses and trees can be released back to the atmosphere when the vegetation burns. In our data, we see occasional large mercury spikes associated with dry season fires. As we move into a bushfire season predicted to be unusually severe, we may see even more of these spikes.

Air from the north

Although mercury levels were usually low in the wet season, on a few days each year the mercury jumped up dramatically.

To figure out where these spikes were coming from, we used two different models. These models combine our understanding of atmospheric physics with real observations of wind and other meteorological parameters.

Both models point to the same source: air transported from the north.

Australia is usually shielded from northern hemispheric air by a “chemical equator” that stops air from mixing. This barrier isn’t static – it moves north and south throughout the year as the position of the sun changes.

A few times a year, the chemical equator moves so far south that the top end of Australia actually falls within the atmospheric northern hemisphere. When this happens, polluted northern hemisphere air can flow directly to tropical Australia.

We observed 13 days when our measurement site near Darwin sampled more northern hemisphere air than southern hemisphere air. On each of these days, the amount of mercury in the air was much higher than on the days before or after.

Tracing the air backwards in time showed that the high-mercury air travelled over the Indonesian archipelago before arriving in Australia. We don’t yet know whether that mercury came from pollution, fires, or a mix of the two.

The highest mercury is observed when the air comes from the northern hemisphere.Howard et al., 2017 (modified)

A global solution

The cross-boundary influences on mercury that we have observed in northern Australia highlight the need for the type of multinational collaboration that the Minamata Convention will foster.

Our new data establish a baseline for monitoring the effectiveness of new actions taken under the Minamata Convention. With the first Conference of the Parties having taken place last week, hopefully it will only be a matter of time before we begin to see the benefit.

One of the worst instances of mangrove forest dieback ever recorded globally struck Australia’s Gulf of Carpentaria in the summer of 2015-16. A combination of extreme temperatures, drought and lowered sea levels likely caused this dieback, according to our investigation published in the journal Marine and Freshwater Research.

The dieback, which coincided with the Great Barrier Reef’s worst ever bleaching event, affected 1,000km of coastline between the Roper River in the Northern Territory and Karumba in Queensland.

Views of mangrove shorelines impacted by dieback event in late 2015, east of Limmen Bight River, Northern Territory (imagery: NC Duke, June 2016).

About 7,400 hectares, or 6%, of the gulf’s mangrove forest had died. Losses were most severe in the NT, where around 5,500ha of mangroves suffered dieback. Some of the gulf’s many catchments, such as the Robinson and McArthur rivers, lost up to 26% of their mangroves.

Views of seaward mangrove fringes showing foreshore sections of minor (left side) and extreme (right side) damage as observed in June 2016 between Limmen and MacArthur rivers, NT. These might effectively also represent before and after scenarios, but together show how some shoreline sections have been left exposed and vulnerable.NC Duke

The gulf, a remote but valuable place

The Gulf of Carpentaria is a continuous sweep of wide tidal wetlands fringed by mangroves, meandering estuaries, creeks and beaches. Its size and naturalness makes it globally exceptional.

An apron of broad mudflats and seagrass meadows supports thousands of marine turtles and dugongs. A thriving fishing industry worth at least A$30 million ultimately depends on mangroves.

Dieback of mangroves around Karumba in Queensland, with surviving saltmarsh, October 2016.NC Duke

Mangroves and saltmarsh plants are uniquely adapted to extreme and fickle coastal shoreline ecosystems. They normally cope with salt and daily inundation, having evolved specialised physiological and morphological traits, such as salt excretion and unique breathing roots.

But in early 2016, local tour operators and consultants doing bird surveys alerted authorities to mangroves dying en masse along entire shorelines. They reported skeletonised mangroves over several hundred kilometres, with the trees appearing to have died simultaneously. They sent photos and even tracked down satellite images to confirm their concerns. The NT government supported the first investigative surveys in June 2016.

Areas affected by severe mangrove dieback in late 2015 (grey shaded) along southern shorelines of Australia’s Gulf of Carpentaria from Northern Territory to Queensland. Aerial surveys (red lines) were undertaken on three occasions during 2016 to cover around 600km of the 1000km impacted.NC Duke

In the end, the emails from citizen scientists nailed the timing: “looks like it started maybe December 2015”; the severity: “I’ve seen dieback before, but not like this”; and the cause: “guessing it may be the consequence of the four-year drought”.

Our investigation used satellite imagery dating back to 1972 to confirm that the dieback was an unparalleled event. Further aerial helicopter surveys and mapping during 2016, after the dieback, validated the severity of the event extending across the entire gulf. Mangrove dieback has been recorded in Australia in the past but over decades, not months.

Mangroves losses (red) and surviving mangroves (green) around the shoreline and mouth of the Limmen Bight River, south-western Gulf of Carpentaria, April 2015 to April 2016.NC Duke, J. Kovacs

Mysterious patterns in the dieback

We still don’t fully understand what caused the dieback. But we can rule out the usual suspects of chemical or oil spills, or severe storm events. It was also significant that losses occurred simultaneously across a 1,000km front.

There were also a number of tell-tale patterns in the dieback. The worst-impacted locations had more or less complete loss of shoreline-fringing mangroves. This mirrored a general loss of mangroves fringing tidal saltpans and saltmarshes along this semi-arid coast.

Mangroves were unaffected where they kept their feet wet along estuaries and rivers. This, as well as the timing and severity of the event, points to a connection with extreme weather and climate patterns, and particularly the month-long drop of 20cm in local sea levels.

Extreme weather the likely culprit

We believe the dieback is best explained by drought, hot water, hot air and the temporary drop in sea level. Each of these was correlated with the strong 2015-16 El Niño. Let’s take a look at each in turn.

First, the dieback happened at the end of an unusually long period of severe drought conditions, which prevailed for much of 2015 following four years of below-average rainfall. This caused severe moisture stress in mangroves growing alongside saltmarsh and saltpans.

Second, the dieback coincided with hot sea temperatures that also caused coral bleaching along the Great Barrier Reef. While mangroves are known to be relatively heat-tolerant, they have their limits.

The air temperatures recorded at the time of the mangrove dieback, particularly from February to September 2015, were also exceptionally high.

Views of mangrove shorelines impacted by dieback event in late 2015, north of Karumba, Queensland (imagery: NC Duke, Oct 2016).

Third, the sea level dropped by up to 20cm at the time of the dieback when the mangroves were both heat- and moisture-stressed. Sea levels commonly drop in the western Pacific (and rise in the eastern Pacific) during strong El Niño years: and the 2015-2016 El Niño was the third-strongest recorded.

The mangroves appear to have died of thirst. Mangroves may be hardy plants, but when sea levels drop, reducing inundation, coupled with already heat-and-drought-stressed weather conditions, then the plants will die – much like your neglected pot plants.

We don’t yet know what role human-caused climate change played in these particular weather events or El Niño. But the unprecedented extent of the dieback, the confluence of extreme climate events and the coincidence with the bleaching of the Great Barrier Reef mean the role of climate change will be of critical interest in the global response to mangrove decline.

What future for mangroves?

The future for mangroves around the world is mixed. Thanks to climate change, droughts are expected to become hotter and more frequent. If the gulf’s mangroves experience further dieback in the future, this will have serious implications for Australia’s northern fisheries including the iconic prawn fishery, mudcrab and fin fish fisheries. All species are closely associated with healthy mangroves.

We don’t know whether the mangroves will recover or not. But there is now a further risk of shoreline erosion and retreat, particularly if the region is struck by a cyclone – and this may have already begun with recent cyclonic weather and flooding in the gulf. The movement of mangrove sediments will lead to massive releases of carbon uniquely buried among their roots.

Our EcoCheck series takes the pulse of some of Australia’s most important ecosystems to find out if they’re in good health or on the wane.

Australia’s Top End, Kimberley and Cape York Peninsula evoke images of vast, awe-inspiring and ancient landscapes. Whether on the hunt for a prized barramundi, admiring some of the oldest rock art in the world, or pursuing a spectacular palm cockatoo along a pristine river, hundreds of thousands of people flock to this region each year. But how are our vast northern landscapes faring environmentally, and what challenges are on the horizon?

Above 17° south, bounded by a rough line from Cairns, Queensland, to Derby, Western Australia, are the high-rainfall (more than 1,000mm a year) tropical savannas. These are the largest and most intact ecosystem of their kind on Earth. With the exception of some “smaller” pockets of rainforest (such as Queensland’s Kutini-Payamu (Iron Range) National Park), the vegetation of the region is dominated by mixed Eucalyptus forest and woodland with a grassy understorey.

Within the fire-prone Great Northern Savannas exist fire-sensitive communities such as these Allosyncapria ternata rainforests along the edge of the Arnhem Plateau in Kakadu National Park.Brett Murphy

There is a distinct monsoonal pattern of rainfall. Almost all of it falls during the wet season (December-March), followed by an extended dry (April-November). Wet-season rains drive abundant grass growth, which subsequently dries and fuels regular bushfires – making these landscapes among the most fire-prone on Earth. The dominant land tenures of the region are Indigenous, cattle grazing and conservation.

Cattle grazing is widespread in the Great Northern Savannas.Mark Ziembicki

These savannas are home to a vast array of plant and animal species. The Kimberley supports at least 2,000 native plant species, while the Cape York Peninsula has some 3,000. More than 400 bird and 100 mammal species call the region home, along with invertebrates such as moths, butterflies, ants and termites, and spiders. Many of the latter are still undescribed and poorly studied.

Many species, such as the scaly-tailed possum, are endemic to the region, meaning they are found nowhere else.

A large male antilopine wallaroo, endemic to tropical Australia.Euan Ritchie

The general lack of extensive habitat loss and modification, as compared to the broad-scale land clearing in southern Australia since European arrival, can give a false impression that the tropical savannas and their species are in good health. But research suggests otherwise, and considerable threats exist.

Fire-promoting weeds such as gamba grass, widely sown until very recently as fodder for cattle, are transforming habitats from diverse woodlands to burnt-out, low-diversity grasslands. Indeed, the fires themselves, which are considered too frequent and too late in the dry season at some locations, are now thought to be a primary driver of species loss.

It is likely some threats may also combine to make matters worse for certain species. For instance, frequent fires, intensive cattle grazing and the overabundance of introduced species such as feral donkeys and horses all combine to remove vegetation cover. This, together with the presence of feral cats, makes some native animals more vulnerable to predation.

New threats

This globally significant ecosystem, already under threat, is facing new challenges too. Proposals to use the region as a food bowl for Asia are associated with calls for the damming of waterways and land clearing for agriculture.

This is against a backdrop of climate change, which among other effects may bring less predictable wet seasons, more frequent and intense storms (cyclones) and fires, and hotter, longer dry seasons. Such changes are not only likely to harm some species, but could also make those much-touted agricultural goals far more difficult to achieve.

Great opportunities exist in northern Australia, but we need to avoid the mistakes of the past.Mark Ziembicki

A key priority for the Great Northern Savannas should be to maintain people on country. It’s often thought that the solution to reducing environmental impacts is removing people from landscapes, but as people disappear so too does their stewardship and ability to manage and care for the land.

Ahead of the election, the major parties have released different visions for developing northern Australia. The Coalition has committed to dam projects across Queensland; Labor has pledged to support the tourism industry.

The Coalition has pledged A$20 million to support 14 new or existing dams across Queensland should the government be returned to power, as part of a A$2.5 billion plan for dams across northern Australia.

It is well recognised that the development of northern Australia will depend on harnessing the north’s abundant water resources. However, it’s also well recognised that the ongoing use of water resources to support industry and agriculture hinges on the health and sustainability of those water resources.

Northern Australia is home to diverse ecosystems, which support a range of ecosystem services and cultural values, and these must be adequately considered in the planning stages.

Sustainability comes second

The white paper for northern Australia focuses almost solely on driving growth and development. Current water resource management policy in Australia, however, emphasises integrated water resource planning and sustainable water use that protects key ecosystem functions.

Lessons from the past show that the long-term success of large water infrastructure projects requires due process, including time for consultation, environmental assessments and investigation of alternative solutions.

What is on the table?

The Coalition proposes providing funds to investigate the feasibility of a range of projects, including upgrading existing dams and investigating new dams. The majority of these appear to be focused on increasing the reliability of water supplies in regional urban centres. Few target improved agricultural productivity.

These commitments add to the already proposed feasibility study (A$10 million) of the Ord irrigation scheme in the Northern Territory and the construction of the Nullinga Dam in Queensland. And the A$15 million northern Australia water resources assessment being undertaken by CSIRO, which is focused on the Fitzroy river basin in Western Australia, the Darwin river basins in Northern Territory and the Mitchell river basin in Queensland.

Rethinking dams

New water infrastructure in the north should be part of an integrated investment program to limit overall environmental impacts. Focusing on new dams applies 19th-century thinking to a 21st-century problem, and we have three major concerns about the rush to build dams in northern Australia.

First, the process to establish infrastructure priorities for federal investment is unclear. For instance, it’s uncertain how the projects are connected to Queensland’s State Infrastructure Plan.

Investment in new water infrastructure across northern Australia needs to be part of a long-term water resource plan. This requires clearly articulated objectives for the development of northern Australia, along with assessment criteria that relate to economic, social and environmental outcomes, such as those used in the Murray-Darling Basin Plan.

Second, the federal government emphasises on-stream dams. Dams built across the main river in this way have manywell-recognisedproblems, including:

lack of environmental flows (insufficient water at the appropriate frequency and duration to support ecosystems)

flow inversion (higher flows may occur in the dry season than in the wet, when the bulk of rainfall occurs)

barriers to fish movement and loss of connectivity to wetlands

water quality and temperature impacts (unless there is a multi-level off-take).

As a minimum, new dams should be built away from major waterways (such as on small, tributary streams) and designed to minimise environmental impacts. This requires planning in the early stages, as such alternatives are extremely difficult to retrofit to an existing system.

Finally, the federal government proposals make no mention of climate change impacts. Irrigation and intensive manufacturing industries demand highly reliable water supplies.

While high-value use of water should be encouraged, new industries need to be able to adapt for the increased frequency of low flows; as well as increased intensity of flood events. Government investment needs to build resilience as well as high-value use.

Detailed planning, not press releases

In place of the rather ad hoc approach to improvements in water infrastructure, such as the projects announced by the federal government in advance of the election, we need a more holistic and considered approach.

The A$20 million investment for 14 feasibility studies and business cases in Queensland represents a relatively small amount of money for each project, and runs the risk of having them undertaken in isolation. The feasibility studies should be part of the entirety of the government’s plan for A$2.5 billion in new dams for northern Australia.

Water resource planning is too important and too expensive to cut corners on planning. Investment proposals for Queensland need to be integrated with water resource planning across the state, and across northern Australia, and with appropriate consideration of climate change impacts.

Fast tracking dams without considering ecosystem impacts, future variability in water supplies, and resilience in local communities merely sets the scene for future problems that will likely demand another round of intervention and reform.